I had a similar idea for take-home tests for software interviews. Run a bash script to commit all changes in a repo every 5 seconds. The candidate then submits a tarball of the git repo.

  #!/usr/bin/env bash
  while true; do
    git add -A
    if ! git diff --cached --quiet; then
      git commit -m "$(date --iso-8601=seconds)"
    fi
    sleep 5
  done